sulfuric acid in methanol T=0°C; 5 h;

toluene-4-sulfonic acid in methanol 24 h; Ambient temperature;

pyridinium p-toluenesulfonate in ethanol T=60°C; 1 h;

1: 95 percent / Et3N / dimethylformamide 2: 1.) O3, 2.) Me2S, 3.) NaBH4 3: aq. NaIO4 / CH2Cl2 / 0 °C 4: 67 percent / NaBH(OAc)3 / benzene 5: 1.) BuLi, HMPA / 1.) THF, 0 deg C, 2.) THF, RT, 9 h 6: 1.) (COCl)2, DMSO, 2.) Et3N 7: 100 percent / BuLi / tetrahydrofuran / -78 - 0 °C 8: 75 percent / toluene / 36 h / 200 °C 9: 80 percent / 1 N aq. HCl / tetrahydrofuran; acetone 10: 72 percent / NaBH4, CeCl3 / ethanol 11: 74 percent / diethyl azodicarboxylate, Ph3P, BzONa / tetrahydrofuran 12: 81 percent / (MeO)3BF4 13: 79 percent / ethanol. NaOEt 14: 99 percent / imidazole / dimethylformamide 15: 75 percent / tetrahydrofuran / Ambient temperature 16: 89 percent / tetrabutylammonium fluoride / diethyl ether / Ambient temperature 17: 1.) Bu3SnH, AIBN, 2.) SiO2 / 1.) benzene 18: 90 percent / m-CPBA, NaHCO3 19: 70 percent / BF3*Et2O / -78 - 20 °C 20: NH2OH*HCl, NaOAc / ethanol 21: carbonyldiimidazole / CH2Cl2 / Ambient temperature 22: 1.) LiNEt2, 2.) 2,6-di-tert-butyl-4-methylphenol / 1.) THF, 0 deg C, 30 min, 2.) THF, 30 min 23: 2.) H2O / 1.) THF, -78 deg C 24: 96 percent / H2 / 10percent Pd/C / ethanol 25: 74 percent / Et3N / benzene 26: 97 percent / TsOH / methanol / 24 h / Ambient temperature View Scheme

1: 99 percent / imidazole / dimethylformamide 2: 75 percent / tetrahydrofuran / Ambient temperature 3: 89 percent / tetrabutylammonium fluoride / diethyl ether / Ambient temperature 4: 1.) Bu3SnH, AIBN, 2.) SiO2 / 1.) benzene 5: 90 percent / m-CPBA, NaHCO3 6: 70 percent / BF3*Et2O / -78 - 20 °C 7: NH2OH*HCl, NaOAc / ethanol 8: carbonyldiimidazole / CH2Cl2 / Ambient temperature 9: 1.) LiNEt2, 2.) 2,6-di-tert-butyl-4-methylphenol / 1.) THF, 0 deg C, 30 min, 2.) THF, 30 min 10: 2.) H2O / 1.) THF, -78 deg C 11: 96 percent / H2 / 10percent Pd/C / ethanol 12: 74 percent / Et3N / benzene 13: 97 percent / TsOH / methanol / 24 h / Ambient temperature View Scheme

1: 67 percent / NaBH(OAc)3 / benzene 2: 1.) BuLi, HMPA / 1.) THF, 0 deg C, 2.) THF, RT, 9 h 3: 1.) (COCl)2, DMSO, 2.) Et3N 4: 100 percent / BuLi / tetrahydrofuran / -78 - 0 °C 5: 75 percent / toluene / 36 h / 200 °C 6: 80 percent / 1 N aq. HCl / tetrahydrofuran; acetone 7: 72 percent / NaBH4, CeCl3 / ethanol 8: 74 percent / diethyl azodicarboxylate, Ph3P, BzONa / tetrahydrofuran 9: 81 percent / (MeO)3BF4 10: 79 percent / ethanol. NaOEt 11: 99 percent / imidazole / dimethylformamide 12: 75 percent / tetrahydrofuran / Ambient temperature 13: 89 percent / tetrabutylammonium fluoride / diethyl ether / Ambient temperature 14: 1.) Bu3SnH, AIBN, 2.) SiO2 / 1.) benzene 15: 90 percent / m-CPBA, NaHCO3 16: 70 percent / BF3*Et2O / -78 - 20 °C 17: NH2OH*HCl, NaOAc / ethanol 18: carbonyldiimidazole / CH2Cl2 / Ambient temperature 19: 1.) LiNEt2, 2.) 2,6-di-tert-butyl-4-methylphenol / 1.) THF, 0 deg C, 30 min, 2.) THF, 30 min 20: 2.) H2O / 1.) THF, -78 deg C 21: 96 percent / H2 / 10percent Pd/C / ethanol 22: 74 percent / Et3N / benzene 23: 97 percent / TsOH / methanol / 24 h / Ambient temperature View Scheme

1: 1.) BuLi, HMPA / 1.) THF, 0 deg C, 2.) THF, RT, 9 h 2: 1.) (COCl)2, DMSO, 2.) Et3N 3: 100 percent / BuLi / tetrahydrofuran / -78 - 0 °C 4: 75 percent / toluene / 36 h / 200 °C 5: 80 percent / 1 N aq. HCl / tetrahydrofuran; acetone 6: 72 percent / NaBH4, CeCl3 / ethanol 7: 74 percent / diethyl azodicarboxylate, Ph3P, BzONa / tetrahydrofuran 8: 81 percent / (MeO)3BF4 9: 79 percent / ethanol. NaOEt 10: 99 percent / imidazole / dimethylformamide 11: 75 percent / tetrahydrofuran / Ambient temperature 12: 89 percent / tetrabutylammonium fluoride / diethyl ether / Ambient temperature 13: 1.) Bu3SnH, AIBN, 2.) SiO2 / 1.) benzene 14: 90 percent / m-CPBA, NaHCO3 15: 70 percent / BF3*Et2O / -78 - 20 °C 16: NH2OH*HCl, NaOAc / ethanol 17: carbonyldiimidazole / CH2Cl2 / Ambient temperature 18: 1.) LiNEt2, 2.) 2,6-di-tert-butyl-4-methylphenol / 1.) THF, 0 deg C, 30 min, 2.) THF, 30 min 19: 2.) H2O / 1.) THF, -78 deg C 20: 96 percent / H2 / 10percent Pd/C / ethanol 21: 74 percent / Et3N / benzene 22: 97 percent / TsOH / methanol / 24 h / Ambient temperature View Scheme

1: 100 percent / BuLi / tetrahydrofuran / -78 - 0 °C 2: 75 percent / toluene / 36 h / 200 °C 3: 80 percent / 1 N aq. HCl / tetrahydrofuran; acetone 4: 72 percent / NaBH4, CeCl3 / ethanol 5: 74 percent / diethyl azodicarboxylate, Ph3P, BzONa / tetrahydrofuran 6: 81 percent / (MeO)3BF4 7: 79 percent / ethanol. NaOEt 8: 99 percent / imidazole / dimethylformamide 9: 75 percent / tetrahydrofuran / Ambient temperature 10: 89 percent / tetrabutylammonium fluoride / diethyl ether / Ambient temperature 11: 1.) Bu3SnH, AIBN, 2.) SiO2 / 1.) benzene 12: 90 percent / m-CPBA, NaHCO3 13: 70 percent / BF3*Et2O / -78 - 20 °C 14: NH2OH*HCl, NaOAc / ethanol 15: carbonyldiimidazole / CH2Cl2 / Ambient temperature 16: 1.) LiNEt2, 2.) 2,6-di-tert-butyl-4-methylphenol / 1.) THF, 0 deg C, 30 min, 2.) THF, 30 min 17: 2.) H2O / 1.) THF, -78 deg C 18: 96 percent / H2 / 10percent Pd/C / ethanol 19: 74 percent / Et3N / benzene 20: 97 percent / TsOH / methanol / 24 h / Ambient temperature View Scheme

1: 1.) (COCl)2, DMSO, 2.) Et3N 2: 100 percent / BuLi / tetrahydrofuran / -78 - 0 °C 3: 75 percent / toluene / 36 h / 200 °C 4: 80 percent / 1 N aq. HCl / tetrahydrofuran; acetone 5: 72 percent / NaBH4, CeCl3 / ethanol 6: 74 percent / diethyl azodicarboxylate, Ph3P, BzONa / tetrahydrofuran 7: 81 percent / (MeO)3BF4 8: 79 percent / ethanol. NaOEt 9: 99 percent / imidazole / dimethylformamide 10: 75 percent / tetrahydrofuran / Ambient temperature 11: 89 percent / tetrabutylammonium fluoride / diethyl ether / Ambient temperature 12: 1.) Bu3SnH, AIBN, 2.) SiO2 / 1.) benzene 13: 90 percent / m-CPBA, NaHCO3 14: 70 percent / BF3*Et2O / -78 - 20 °C 15: NH2OH*HCl, NaOAc / ethanol 16: carbonyldiimidazole / CH2Cl2 / Ambient temperature 17: 1.) LiNEt2, 2.) 2,6-di-tert-butyl-4-methylphenol / 1.) THF, 0 deg C, 30 min, 2.) THF, 30 min 18: 2.) H2O / 1.) THF, -78 deg C 19: 96 percent / H2 / 10percent Pd/C / ethanol 20: 74 percent / Et3N / benzene 21: 97 percent / TsOH / methanol / 24 h / Ambient temperature View Scheme

1: 1.) O3, 2.) Me2S, 3.) NaBH4 2: aq. NaIO4 / CH2Cl2 / 0 °C 3: 67 percent / NaBH(OAc)3 / benzene 4: 1.) BuLi, HMPA / 1.) THF, 0 deg C, 2.) THF, RT, 9 h 5: 1.) (COCl)2, DMSO, 2.) Et3N 6: 100 percent / BuLi / tetrahydrofuran / -78 - 0 °C 7: 75 percent / toluene / 36 h / 200 °C 8: 80 percent / 1 N aq. HCl / tetrahydrofuran; acetone 9: 72 percent / NaBH4, CeCl3 / ethanol 10: 74 percent / diethyl azodicarboxylate, Ph3P, BzONa / tetrahydrofuran 11: 81 percent / (MeO)3BF4 12: 79 percent / ethanol. NaOEt 13: 99 percent / imidazole / dimethylformamide 14: 75 percent / tetrahydrofuran / Ambient temperature 15: 89 percent / tetrabutylammonium fluoride / diethyl ether / Ambient temperature 16: 1.) Bu3SnH, AIBN, 2.) SiO2 / 1.) benzene 17: 90 percent / m-CPBA, NaHCO3 18: 70 percent / BF3*Et2O / -78 - 20 °C 19: NH2OH*HCl, NaOAc / ethanol 20: carbonyldiimidazole / CH2Cl2 / Ambient temperature 21: 1.) LiNEt2, 2.) 2,6-di-tert-butyl-4-methylphenol / 1.) THF, 0 deg C, 30 min, 2.) THF, 30 min 22: 2.) H2O / 1.) THF, -78 deg C 23: 96 percent / H2 / 10percent Pd/C / ethanol 24: 74 percent / Et3N / benzene 25: 97 percent / TsOH / methanol / 24 h / Ambient temperature View Scheme